1. Field of the Invention
The present invention relates to a pillar construction for a vehicle which is made of a diecast aluminum alloy.
2. Description of the Related Art
In reducing the weight of a vehicle, it is considered to form members which make up a body of the vehicle using an aluminum alloy. In addition, when the body is made of aluminum alloy, it is considered to use a diecast aluminum alloy for a particular member which requires strength such as a C pillar (a rear pillar).
On the other hand, the C pillar lies in the vicinity of a rear axle of the vehicle and is a member which is formed into a vertically long and complex shape in such a way that an upper portion is connected to a side roof rail and a lower portion extends as down as a rear suspension cross-member or a side sill. Due to this, in forming a C pillar of diecast aluminum alloy, it is considered that a C pillar is divided into an upper member and a lower member in the vicinity of substantially a vertical center of the C pillar, for example, in a position which corresponds to the vicinity of an upper edge of a rear wheel house, the upper member and the lower member, which are so divided, are formed of diecast aluminum alloy, and thereafter, the upper and lower members are joined integrally to each other (for example, refer to JP-A-2003-261072).
However, with such a construction in which the C pillar is divided into the upper member and the lower member, and the upper member and the lower member are joined together just by welding along the parting line which divides the C pillar in the way as described above, there has still remained a problem that the joined portion becomes rectilinear, and strength, in particular, rigidity with respect to the transverse direction of the vehicle or rigidity with respect to torsion cannot be obtained sufficiently. In addition, aligning the joining portions is not easy, and when fitting portions formed respectively on the upper member and the lower member are brought into abutment with each other to thereby be joined together, there has been caused a problem that variation in shape, which is produced when the upper and lower members are manufactured, is unable to be absorbed.
In addition, in joining the C pillar to the side roof rail, and the side roof rail to the roof bow, while the end portion of the C pillar and the end portion of the roof bow are formed flat for the C pillar and the roof bow to be fixed onto the side roof rail, bending easily appears at the flat portions, and in order to secure required rigidity, the plate thickness needs to be increased, this leading to an increase in the number of labor hours.